In the maturation of the bacteriophage-,X, the large subunit of the terminase protem is involved in the cutting and packaging of concatameric DNA. A new purification procedure made the terminase sound amenable to STEM study. Preliminary studies on the freeze-dried protein indicate that it was prone to denature on the supporting carbon film. A brief fixation with glutaraldehyde appears to help.-Once conditions are worked o4 the hope would be to also visualize the strucure, in low-density stain.